The present invention relates to a device for producing an essentially linear motion in a moveable part in a measuring machine where a transmission from a rotary motion to a linear motion takes place.
During the positioning of measuring robots there are very large requirements for low friction between a movable measuring carriage with a measuring bridge, a shaft and a measuring tip, and a fixed part.
Normally, a transmission to the carriage is used which gives a high rigidity in the positioning direction and a running action which is, relatively, as smooth as possible. This is done, for example through a plain shaft drive, e.g. such as is used in the CEJ-Cordimet marketed by C E Johansson, or by a belt drive (re-inforced toothed belt, e.g. CEJ-Saphir) or a cog against a fixed rack, or by a screw and nut.
Other variations of the type using a steel band have been produced, but this has led to very high parallel alignment requirements on the drive shaft and the moving part or carriage, with high manufacturing costs as a consequence.
Bands, belts, plain shafts, screw/nuts and racks also easily lead to torques and forces which tend to deviate from the direction of movement being transmitted to the carriage, with subsequent scattering of the measurement result.